Analyzer: http://netgroup-serv.polito.it/analyzer/ (a public-domain protocol analyzer for Windows 95/ 98/NT)
cron: http://www.kalab.com/freeware/cron/cron.htm (a Windows port of the UNIX utility)
GNU Utilities for Win32: http://www.weihenstephan.de/~syring/win32/UnxUtils.html (ports of various GNU utilities for Win32 that run natively without an emulation layer; covers tar, gzip, and md5sum)
MinGW: http://www.mingw.org/ (minimalist GNU for Windows, which provides a gcc that produces Windows-native binaries)
Nessus: http://www.nessus.org/ (an open-source security scanner)
Netcat: http://www.atstake.com/research/tools/network_utilities/ (the TCP/IP Swiss Army Knife)
NMAP: http://www.insecure.org/nmap/ (the Network Mapper)
Osiris: http://osiris.shmoo.com/ (a tripwire-like program for Windows NT)
Perl for Windows: http://aspn.activestate.com/ASPN/Downloads/ActivePerl/index/
SniffIt: http://reptile.rug.ac.be/~coder/sniffit/sniffit.html (a packet sniffer for LINUX, SunOS, Solaris, FreeBSD and IRIX)
The Laughing Bit: http://www.tlb.ch/ (some useful FireWall-1 scripts and programs)
Zebra: http://www.zebra.org/ (a multipurpose routing daemon available under the GNU license)
fwgold: http://www.rotoni.com/FwGold/
fwlogsum: http://fwlogsum.sourceforge.net
logrep: http://logrep.sourceforge.net
NetIQ's Webtrends suite: http://www.netiq.com/webtrends/default.asp
Netspective Webreporter: http://www.getnetspective.com/
PATROL for Check Point FireWall-1 from BMC Software: http://www.bmc.com/products/proddocview/0,,19052_0_0_7072,00.html
Peter Sundstrom's fwlogsum: http://www.ginini.com/software/fwlogsum/
Rajeev Kumar's fwlogstat: http://www.rajeevnet.com/fw1/fwlogstat/v1.0/
Archive of OTP clients: http://www.tifosi.com/OTP/
Opie: http://www.inner.net/pub/opie/ (One-Time Passwords in Everything)
optgen: http://www.phoneboy.com/files/otpgen.zip